Question
Assume that each atom in a copper wire contributes one free electron. Estimate the number of free electrons in a copper wire having a mass of $6.4g ($take the atomic weight of copper to be $64\ g\ mol^{-1}.)$
✓
Answer
$64$ grams of copper have $1$ mole
$6.4$ grams of copper have $0.1$ mole
$1$ mole $=$ No atoms
$0.1$ mole $= ($no $\times 0.1)$ atoms
$= 6 \times 10^{23}\times 0.1$ atoms $= 6 \times 10^{22}$ atoms
$1$ atom contributes $1$ electron
$6 \times 10^{22}$ atoms contributes $6 \times 10^{22}$ electrons.
$6.4$ grams of copper have $0.1$ mole
$1$ mole $=$ No atoms
$0.1$ mole $= ($no $\times 0.1)$ atoms
$= 6 \times 10^{23}\times 0.1$ atoms $= 6 \times 10^{22}$ atoms
$1$ atom contributes $1$ electron
$6 \times 10^{22}$ atoms contributes $6 \times 10^{22}$ electrons.
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
A resistance of $R$ draws current from a potentiometer. The potentiometer wire, $AB,$ has a total resistance of $R_o$. A voltage $V$ is supplied to the potentiometer. Derive an expression for the voltage across $R$ when the sliding contact is in the middle of potentiometer wire.
→A charge of $20\mu\text{C}$ is placed on the positive plate of an isolated parallel-plate capacitor of capacitance $10\mu\text{F}.$ Calculate the potential difference developed between the plates.
→A coil having inductance 2.0H and resistance $20\Omega$ is connected to a battery of emf 4.0V. Find
→- The current at the instant 0.20s after the connection is made.
- The magnetic field energy at this instant.
In a series $\text{LCR}$ circuit connected to an ac source of variable frequency and voltage $v v_m= \sin,$ draw a plot showing the variation of current $(I)$ with angular frequency$ (\omega)$ for two different values of resistance $R_1$ and $R_2(R_1 > R_2 )$. Write the condition under which the phenomenon of resonance occurs. For which value of the resistance out of the two curves, a sharper resonance is produced? Define $Q-$factor of the circuit and give its significance.
→Average lifetime of a hydrogen atom excited to $n = 2$ state is $10^{-8}s$. Find the number of revolutions made by the electron on the average before it jumps to the ground state.
→In the circuit shown, $R_1 = 4\Omega , R_2 = R_3 = 15\Omega , R_4 = 30\Omega$ and $E = 10V.$ Calculate. The equivalent resistance of the circuit and the current in each resistor.
→A block of mass 0.5kg hanging from a vertical spring executes simple harmonic motion of amplitude 0.1m and time period 0.314s. Find the maximum force exerted by. the spring on the block.
Define atomic mass unit.
Write Einstein's photoelectric equation in terms of the stopping potential and the threshold frequency for a given photosensitive material. Draw a plot showing the variation of stopping potential $vs$. the frequency of incident radiation.
→At what distance should two charges, each equal to $1C,$ be placed so that the force between them equals your weight?
→